1. Field of the Invention
This invention relates to a seismic brace that has two ends connected fixedly to a framework of a building, and more particularly to a seismic brace that includes an elongated central brace unit and a restraining member which is disposed around the central brace unit in a tight fit manner to prevent buckling of the central brace unit when the building is subjected to an earthquake.
2. Description of the Related Art
Referring to FIGS. 1, 2, and 3, a first conventional seismic brace 70 is shown to have an elongated diagonal central brace unit 130 connected fixedly to a framework of a building at two ends thereof, and a rigid restraining member 120 that includes a rectangular steel tube 122 sleeved around a middle portion of the central brace unit 130 in a tight fit manner to prevent buckling of the central brace unit 130 when the building is subjected to an earthquake, and a concrete material 110 that fills a space between the central brace unit 130 and the steel tube 122. The central brace unit 130 has a cross-shaped cross-section, is welded to cross-shaped-cross-sectioned plates (not shown) on the framework of the building at two ends of the central brace unit 130, and includes a main plate 132 having a middle portion and two ends that are wider than the middle portion, and two wing plates 131, 133 welded respectively to two opposite side surfaces of the main plate 132. An unbounding layer 140 is disposed between the concrete material 110 and the central brace unit 130 so as to permit relative longitudinal sliding movement of the central brace unit 130 and the restraining member 120. For example, the unbounding layer 140 is a grease layer.
Although the central brace unit 130 is able to absorb effectively the energy of earthquakes, to delay the damage of the framework of the building resulting from the shock of earthquakes, and to break prior to breakage of the parts of the framework coupled to the central brace unit 130, the first conventional seismic brace 70 has a disadvantage in that the restraining member 120 cannot be removed from the central brace unit 130 after each earthquake to permit inspection of the central brace unit 130.
Referring to FIGS. 4, 5, 6, and 7, a second conventional seismic brace 72 is shown to include an elongated diagonal central brace unit connected fixedly to a framework of a building at two ends thereof, and a restraining member 160. The central brace unit includes two spaced-apart T-shaped-cross-sectioned plate assemblies 150, each of which consists of a main plate 151 and a wing plate 152 that are welded to and that are perpendicular to the main plate 151. The restraining member 160 includes two adjacent rectangular steel tubes 162 sleeved respectively around the plate assemblies 150 and interconnected fixedly by connecting steel plates 170, and a concrete material 110 that fills spaces between the plate assemblies 150 and the steel tubes 162. Each of the plate assemblies 150 is spaced apart from the concrete material 110 by an unbounding layer 140. As such, two spaces 73 (see FIG. 5) are formed between the plate assemblies 150 at two ends of the second conventional seismic brace 72 so as to permit insertion of two connecting plates (not shown), which are fixed on the framework of the building, thereby attaching the second conventional seismic brace 72 fixedly to the framework. Likewise, the restraining member 160 cannot be removed from the plate assemblies 150.